Water enquiry question 2 Flashcards by Jessica Dawson

What is the fundamental cause of drought?

A shortfall of water over an extended period of time.

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What does drought duration do?

Increase severity

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What are the possible physical causes of drought?

Sea surface temperature anomalies are extremely important
Teleconnections, development of weather phenomena and the impacts this can have around the globe - ENSO

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What is El Niño Southern Oscillation (ENSO)?

An oscillation of the ocean atmosphere system in the tropical Pacific, having important consequences for weather around the globe.

The winds change direction blowing from West to East

Occurs every 3-6 years but appears to be getting more regular.

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On a normal year there is…

Wind direction from east to west, trade winds move warm surface water towards the western pacific
Low air pressure in West, with rain clouds as there is warm moist air - Australia
High air pressure in East, with upwelling of cool water (Peru current) and descending air = dry period - S. America

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On an El Niño year there is…

Wind direction from west to east, warm water moves to east.
The cold Peru current is suppressed = poor crop
High air pressure in West, with descending air = droughts and fires - Australia
Low air pressure in East, with ascending air and rainclouds = more evaporation and rain and flooding - S. America

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What is La Niña ?

An exaggerated version of normal conditions with very strong trade winds.

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What are teleconnections?

The knock on effects around the world due to El Niño such as droughts in Brazil and floods in Kenya and Bangladesh.

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What are the effects of El Niño?

air pressure is unusually high over west coast of South America and low over Eastern Australia
Warm water is pushed westwards so sea levels rise by up to 1m
Strong uplift of air leads to heavy rain around Indonesia and philippines

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What are the three important physical factors when concerning drought?

El Niño
Intertropical convergence Zone (ITCZ)
Mid Latitude blocking anticyclones

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What is the ITCZ?

Intertropical convergence zone. A band of low pressure around the equator between the northern and Southern Hemisphere Hadley Cells. This area of low pressure causes heavy rain when it is over an area and drought when it moves elsewhere.

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What are mid latitude blocking anticyclones?

Areas of high pressure which rotate very slowly almost stationary in the opposite direction to cyclones.
High pressure zones over the UK blocks low pressure zones, when a polar jet stream slows anticyclones are blocked.

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When were the major drought years in the UK?

1976 AND 2003

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What were the effects of the 1976 drought?

temperature hit 35.9 degrees, parts of south west didn’t receive rain for 45 days, crops affected by 50%

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What are the human influences on drought?

deforestation, population density, overgrazing, governance, poor agricultural techniques - irrigation, conflict which can lead to migration, soil erosion, poor infrastructure, urbanisation

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What do humans act like with water usage and security in drought. (GOOD EVALUATION POINT)

a positive feedback mechanism

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What were the issues in the 1999-2000 drought in Eriteria and Ethiopia?

famine
10 mil needed food assistance
war blocked access to food
population doubling every 20/30 years - pop. density

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What induced the drought in Eriteria and Ethiopia?

La nina

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What are the physical problems in the Sahel?

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Low rainfall
Large annual fluctuations in rainfall - sea temp.
decadal changes in rainfall

What are 6 human problems in the Sahel?

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Increase pop dens
overgrazing
deforestation
war
rural poverty
lack of good governance

What is desertification?

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Land degradation in arid, semi humid areas resulting from climatic variation and human activity.

What are the 7 factors regarding the complexity of water security?

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Poor service provision
Human induced climate change
Exclusion due to race, social status, politics
Pop. increase and migration
Uncontrolled discharge of pollutants into water
Settlement on hazard prone land
Natural climate variability

Case study - droughts in Australia, physical causes

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low, highly variable rainfall due to geography
droughts vary considerably
drainage basins much larger, longer time scale- water not replaced as often

What was the impact of the Big Dry 2006, Aus.(3 points)

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affected over half farmers in Murray darling basin
this area produced 50% agricultural output - increased food prices
Adelaide was under 40% in reservoirs

Australia as a H.I.C. one positive one negative

- :( Increased water usage due to development and affordability - :) privilege to recycle water, desalination and strategies for conservation

Impact of drought on wetland ecosystems.

- created gaps in food chain/web -increased SRO, problems downstream -removal of species - ecosystem productivity decline

In ecosystems drought can cause...

loss of foliage, increase in pests and diseases, poor growth rates and impair water transport

Flash flood examples

Sardinia, UK - Storm Desmond

Why does flooding occur

- due to a prolonged build of rainfall over a long period of time - caused by several mid lat depressions passing over the same place, this slowly increasing discharge until bankfull is reached.

Flooding can only occur after...

mid latitude depressions

What caused Storm Desmond

moist air from Caribbean to British Isles, heavy rain caused by area of low pressure over Atlantic.

Effects of storm Desmond:

- economic - £500m damage - social - road and rail closures, 40 schools in cumbria closed - environment - landslide in glenn riding beck, vegetation destroyed and water quality affected

Climate change's impact on the water cycle

- increased moisture in lower atmosphere as it becomes warmer and evaporation rates increase - increased frequency of intense precipitation events - more precipitation falls as rain than snow impacting river regime.

3 social impacts of climate change

- water demand will rise - urban areas will see more flash flooding - temps increase in uk especially summer

4 environmental impacts of climate change

- water quality will fall due to high temp and increased sediment - reduced groundwater levels - sea levels will rise due to thermal expansion - increase in invasive species

True or False: the amount of water available has not changed.

TRUE: population density has increased and developed therefore we demand far more water than we used

Define water insecurity

the lack of a reliable source of water of appropriate quality and quantity to meet the needs of the local human population and environment.

give three reasons why there is a scarcity in water availability

there is a scarcity in availability due to physical shortage/ scarcity in access due to the failure of institutions to ensure a regular supply/ due to the lack of adequate infrastructure.

Define water stress

where the demand for water exceeds the availability during a certain period or when poor quality restricts its use. Water stress causes deterioration of fresh water resources in terms of quantity e.g. aquifer over exploitation

What accounts for the most water use globally?

Agricultural use 67%

What are the uses for water?

Agricultural, industry, domestic, power

What are four ways humans affect the water cycle?

- Land use changes - Flood management - By quantity and quality - localised contamination - Water abstraction

Case Study: (SALT)on Sea

- receives basin run off from irrigated farmland - has both fresh and saltwater marshes - 25% more saline than the pacific as fish no longer can survive - reduction of tourism as perception has change to a toxic dump

Case Study: Aral Sea

- deemed an environmental catastrophe as sea had shrunk by 90% in 2007 - soviet government tried to divert it so they didn't have to rely on western suppliers - change human induced, possibly on purpose

Who are the players in Aral Sea case study?

- former soviet gov - fishing community - locals - farmers - water engineers

Water enquiry question 2 Flashcards

(45 cards)